Could someone please explain how we define say someone showing the trait of polydactyly/achondroplasia as having the dominant allele/or saying that 99.99% of people show the rexessive allele-why dont we just say like other traits eg left hand that the above inheritances are recessive?
I’m not really sure I understand your question but here’s an answer anyway.
The dominance or recessiveness of an allele is dependent on the mode of function of the gene not just on how common it is. An allele is dominant if it causes a phenotype with only one copy (irrespective of what the other copy is) whereas a recessive allele requires both copies to be recessive to have any effect on the phenotype.
